In general, a metallic gasket is used in the joint area between the cylinder head and the cylinder block of an internal combustion engine. The metallic gasket has beads formed to seal the deck surfaces between the cylinder head and the cylinder block. When those beads are tightened by tightening means such as bolts or the like for joining the members to be joined, the beads form elastic seal lines on the deck surfaces due to the tightening forces of the tightening means, thereby attaining a sealing effect.
However, when the cylinder head is tightened to the cylinder block through the metallic gasket by the tightening bolts, the cylinder head is curved due to the tightening forces of the bolts, particularly, the gap around the combustion chamber increases, so that distortions occur. Consequently, there are the following inconveniences. Namely, the combustion gas leaks from the portions where those distortions occurred and pollutes the metallic gasket interposed in the joint area. The substance contained in the combustion gas is deposited, causing the sealing effect to deteriorate. Further, in operation, the gap between the deck surfaces around the combustion chamber increases and decreases in dimension due to influences of, for example, the combustion gas pressure and the heat of the engine, causing the beads of the metallic gasket to be fatigued due to an alternating load. In addition, there is the risk such that this alternating load also acts on the tightening bolts, so that the bolts and the cylinder head portions which are brought into engagement with the bolts are damaged. Moreover, there is the problem that the tightening forces of the bolts are reduced and the sealing effect of the metallic gasket deteriorates.